The 30-year-old singer has refused point blank to settle with makers Blue Orbit and instructed lawyers to quiz the music mogul along with judges LA Reid and Paula Abdul on how much they earn.

A Los Angeles judge gave her the green light to see the trio’s contracts. She will call Cowell, 53, as key witness.

But fans hoping for a public airing of The X Factor chief’s wages are in for a blow - Judge Abraham Klein ruled contract details must be kept secret.

Cheryl’s deals will also be kept from the public – along with payout details if she wins the case.

(Image: FilmMagic)

An insider said: “This paperwork is a clear sign that Cheryl wants her day in court. She is pushing for full fees… £2million, legal fees and a bonus, which could total £3.5million. Cheryl will learn what Simon earned and her co-stars too.

“Those papers could be the smoking gun if she can show others have been treated differently to her. The confidentially of discovery order means much of his ­testimony is unlikely to become public. Had it not been signed, the trial would have been the most explosive reality show trial.

“Every aspect from pay, expenses, contracts and personal ­requirements of the stars will be released.”

Cheryl accepts she was paid her full £1.2million wage despite only making a brief appearance on US X Factor. But she claims she was promised £1.5million for a second series whatever the outcome of the first.

Blue Orbit insist she was treated fairly. If Cheryl loses she faces a £1million bill from her legal team plus Blue Orbit’s costs.